In a multimedia broadcast/multicast service (MBMS), a communication manner in which user equipment (UE) accesses a network by using a relay service provided by another user equipment is referred to as relay-based communication. The user equipment that needs the relay service is referred to as remote user equipment (Remote UE), and the user equipment that provides the relay service is referred to as relay user equipment (Relay UE). For example, the remote user equipment is public safety (Public Safety) user equipment that is not in a network coverage area, and the relay user equipment is public safety user equipment that is in a network coverage area. In this case, though not in a network coverage area, the remote user equipment may still receive service data of an MBMS by using a relay service provided by the relay user equipment. Specifically, the remote user equipment requests a relay service from the relay user equipment to obtain service data of an MBMS. After receiving the request, the relay user equipment monitors the service data of the MBMS requested by the remote user equipment, and sends the service data to the remote user equipment if the service data of the MBMS is detected.
In existing relay-based communication, relay user equipment probably cannot provide a relay service for remote user equipment. For example, an MBMS required by the remote user equipment may not be provided in a cell on which the relay user equipment camps. In this case, if no service data of the MBMS exists in the cell on which the relay user equipment camps, the relay user equipment cannot detect the service data of the MBMS. However, the relay user equipment still performs monitoring, and the remote user equipment still waits to receive the service data of the MBMS from the relay user equipment. The remote user equipment may still not receive the service data of the required MBMS from the relay user equipment after waiting, thereby causing a waste of communications resources and low service efficiency for the remote user equipment. It can be learned that in the relay-based communication manner in the prior art, remote user equipment randomly selects relay user equipment, thereby causing a waste of communications resources and device energy, low service efficiency for the remote user equipment, and other problems. Consequently, user satisfaction with a service is seriously affected.